Amyloses cyclohepta

Acetate Cyclohexa- amylose k obe/kunc Cyclohepta-amylose Cycloocta- amylose... 

In contrast to the reaction of cyclohexaamylose with 1, no enantiomeric specificity is observed in the reaction of this material with cyclohepta-amylose (Paton and Kaiser, 1970). This loss of specificity upon increasing... 

The results presented by Cramer and Kampe are amplified by the data in Table XII which correspond to a recent investigation of the cyclohepta-amylose-catalyzed decarboxylation of a series of substituted phenylcyanoacetic acid anions (Straub and Bender, 1972). These data differ strikingly... 

Carbonates, diaryl, reactions with cyclohepta-amylose, 23 240 Carbon dioxide adsorption, 21 44 on chromia, 20 27 on gallium-doped NiO, 22 247-251 on nickel catalysts, 22 87-96 dissociative, 22 93-96... 

The hydrolysis of substituted phenyl acetates has been studied in the presence of cyclodextrins (Van Etten et al, 1967a, b). No correlation was found between the rate constants for hydrolysis and a for the substituent group. Specificity was directed towards meta-substituents. m-t-Butylphenyl acetate hydrolyses 240 times faster in the presence of 0-01 M cyclohepta-amylose. Comparison of spectral shifts upon inclusion of p-t-butyl and m-t-butylphenol indicated that benzene rings of p-substituted phenols are included within the cavity of cyclodextrins [45], but that the benzene ring of the meta-isomer... 

Brass and Bender (1973) have recently studied reaction of bis ( -nitrophenyl) carbonate with cyclohepta-amylose. Michaelis-Menten kinetics were observed, and two equivalents of p-nitrophenol released. Release of the first equivalent of />-nitrophenol is rate-determining, the second one being released in a fast step. The latter... 

The Schardinger dextrins, cyclohexa- and cyclohepta-amylose, act as competitive inhibitors for heto-amylase. ... 

Lindner, K and W Saenger (1982). Crystal and molecular structure of cyclohepta-amylose dodecahydrate. Carbohydrate Research, 99,103-115. 

Cycloamyloses have been separated by h.p.l.c. on a /u-Bondapak-carbohydrate column using acetonitrile-water mixtures as eluant. The molecular dynamics of the inclusion complexes formed between cyclohexa-amylose and some aromatic amino-acids and dipeptides have been studied by n.m.r. spectroscopy. The forces binding the complexes were found to be weak. The c.d. spectra of cyclohepta-amylose which had been complexed with 2-substituted naphthalenes were measured at various concentrations of cyclohepta-amylase and temperatures between 10-70 C. The complex with 2-naphthoxyacetic acid showed 1 1 stoicheiometry. The molar ellipticity and thermodynamic parameters were determined and enthalpy and entropy ranges calculated. The correlation was explained by a cyclohepta-amylose guest molecule interaction where the guest molecule was highly solvated. The induced c.d. spectra of cyclohepta-amylose complexes with substituted benzenes confirmed that an axial inclusion... 

Diffusion of cyclohexa- and cyclohepta-amyloses has been studied in aqueous solutions of poly(methacrylic acid), sodium poly(styrene sulphonate) having three different degrees of sulphonation, and copoly (sty rene-methacrylic acid) containing three different amounts of styrene. A decrease of the diffusion coefficients of the cycloamyloses in these polymer solutions was found to be dependent on the polymer content, the degree of sulphonation, the styrene content, and the degree of neutralization. The results were interpreted by assuming a 1 1 complex formation between the cycloamylose and an appropriate residue in the polymer. 

Formation of crystalline cyclohepta-amylose inclusion complexes has been followed by recording continuously the turbidity of the aqueous solution of cyclohepta-amylose and the guest molecule (solvent, drug, or aromatic compound) from 60 C downwards. The concentrations of the guest molecules were such that they could not form crystals above the crystallization temperature of pure cyclohepta-amylose. The appearance of turbidity caused by crystal formation before the characteristic temperature of cyclohepta-amylose crystallization is therefore considered to be evidence for inclusion complex formation. The influence of parameters such as concentration, pH, cooling speed, presence of inorganic salts, and inoculating crystals was studied. 

Cyclohepta-amylose very effectively catalyses a variety of specific allylation-oxidation reactions of hydroquinone derivatives, and appears to mimic the action of allylquinone synthase.Possible explanations for the molecule s catalytic ability were described. 

Powdered inclusion complexes have been obtained by freeze-drying together cyclohepta-amylose and anti-inflammatory drugs (indomethacin, flufenamic acid, or phenylbutazone). Significantly less irritation was caused to the stomach of rats by phenylbutazone on oral administration when the drug was given as a freeze-dried inclusion compound, but no such effect was observed for the other two drugs. 

The stability constants K(.) have been determined by h.p.l.c. for 1 1 inclusion complexes of cyclohexa- and cyclohepta-amyloses with barbiturates, phenothiazines, sulphonylamides, and sulphonylureas. Results were in good agreement with those obtained by solubility and spectroscopic methods. Use of h.p.l.c. is particularly suitable for chemically unstable compounds like pheno-thiazine. 

The diffusion behaviour of cyclohexa- and cyclohepta-amyloses in aqueous poly(methacrylic acid), copoly(methacrylic acid-styrene), and copoly(styrene-sulphonic acid) solutions has been investigated. The diffusion coefficients decreased with the concentration of the polymers, and the descending tendencies were successfully explained by means of obstruction and interaction effects. 

Epichlorohydrin-cross-linked cyclohexa- and cyclohepta-amylose gels have been used for the chromatographic resolution of racemic mandelic acid and its derivatives. Modified cyclohepta-amylose bound the L-(- -)-isomers preferentially, and resolved D,L-methyl mandelate to give the D-(—)-isomer of 100% optical purity in the first fraction. Cross-linked cyclohexa-amylose bound D-(—)-isomers more strongly than L-(-t-)-isomers, resolving D,L-methyl mandelate to a smaller extent than cross-linked cyclohepta-amylose. Binding was studied quantitatively by the equilibrium method. 

The oc-amylase from a wheat-rye hybrid [triticale ( x Triticosecaley has been purified by affinity chromatography on cyclohepta-amylose immobilized on a derivative of macroporous agarose. Contaminating proteins were eluted with a sodium acetate buffer, whereafter a-amylase was eluted with a buffer containing cyclohepta-amylose. This chromatographic procedure gave a yield of 90% and < 180-fold purification. 

Studies of the hydrolyses of cyclohexa-, cyclohepta-, and cyclo-octa-amyloses by Taka-amylase A (one of the a-amylases from Aspergillus oryzae) indicated that each cycloamylose binds to the same active site of the enzyme. Since there is little difference in the respective AG, Af/, and AS values for enzymic hydrolysis of these cycloamyloses, their binding modes appear to be similar. The extent of multiple attack on the cycloamyloses was not affected by temperature. A 4-phenylazobenzoyl derivative of Taka-amylase A has been used to investigate the active site of the enzyme. A. oryzae a-amylase has a synergistic effect on the action of the glucoamylase from A. awamori var. kawachi ... 

An acid cyclodextrin D-glucanotransferase from an alkalophilic Bacillus sp. exhibits a specificity similar to those of the transferases from B. circulans and B. macerans, although different proportions of cyclohexa-, cyclohepta-, and cyclo-octa-amyloses are formed. The cyclodextrin D-glucanotransferase from an alkalophilic Bacillus sp. has been used, either alone or in combination with pullul-anase, to produce cyclohepta-amylose. A succinylated derivative of this cyclodextrin D-glucanotransferase has been immobilized, with retention of activity, by adsorption onto a vinylpyridine polymer. 

Cycloamyloses.—Starch has been converted into cyclohepta-amylose by soluble, immobilized forms of cyclodextrin o-glucanotransferase. ... 

Mild acidic hydrolysis (5mM HCl at 100 C) of cyclohepta-amylose gave an 8% yield of maltoheptaose. The first-order rate constant increased during hydrolysis because the a-(l - 4)-linkages of cyclohepta-amylose and linear dextrins are cleaved at different rates. Various thermodynamic parameters and the dependence of the rate of hydrolysis on pH and on complexation of cyclohepta-amylose with toluene were determined. 

Cyclohepta-amylose couples to macroporous agarose activated with 1,4-bis-(2,3-epoxypropyloxy)butane to give a material that can be used in the purification of a-amylase. ... 

Cyclohepta-amylose has been converted into the phosphates (21)—(23), which were examined as catalysts for the hydrolysis of 4-nitrophenyl tetrahydropyranyl ether at low pH and for the exchange of 4-t-butylphenacyl alcohol (tritiated in the a-methylene group) at high pH. All three isomers, as the phosphate dianions, were effective catalysts for the latter reaction in which the functional group assists enolization of the bound ketone. Only the 3-phosphate (22) showed net catalysis of the hydrolysis of the ether, which was bound and hydrolysed with the assistance of a monoanionic phosphoric acid group. 

The hydrophobic binding of guest molecules to cycloamyloses can be represented schematically as shown in Scheme 8. The cyclohepta-amylose derivatives (24) and (25), which are capped by hydrophobic entities, bound sodium l-anilinonaphthalene-8-sulphonate more effectively than did cyclohepta-amylose. 

The molecular structure of a 1 1 complex of cyclohepta-amylose and 2,5-di-iodobenzoic acid has been determined by X-ray crystallography. The cyclohepta-amylose molecules form channels in the crystal by means of head-to-head and tail-to-tail stacking Details of the crystal structures of cyclohexa-amylose hexahydrate and cyclohexa-amylose-propan-l-ol hydrate have been sum-marized. ... 

The conversion of starch into cyclohepta-amylose by soluble or immobilized cyclodextrin D-glucanotransferases and the ability of a-amylases to convert starch into some products by a non-hydrolytic (transglycosylation) pathway have been reported.The production of single-cell protein from starchy wastes has been discussed. 

An immobilized form of cyclodextrin D-glucanotransferase catalysed the conversion of starch into cyclohepta-amylose in a yield of 46 %, without significant loss of enzymic activity a yield of 52% was achieved when pullulanase was also added. ... 

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